Calculating the firing arc for vehicles main gun and MG

[JOHN BOND 001]

I have played players who calculate the firing arcs for HULL MGs and CO axil MGs from the tip of the weapon
And calculate the firing arc for Main guns from the tip of the gun barrel.

Am I correct in my assumption from the images that:
Both images clearly show that the firing arc for both MG (whether Hull or co axial) and Main gun is calculated from the middle of the vehicle at the point at which the main gun joins the turret.

thanks in advance John .

[Truscott Trotter]

You know some strange people JB
Reckon those diagrams is pretty clear.

[Seret]

As long as you're being consistent I don't really see that it makes much difference, especially in the smaller scales.

I've never seen anyone do it from the muzzle end though. Either the centre of the vehicle or the breech end of the barrel would be sensible.

[JOHN BOND 001]

thanks Andy and TT, believe me it happens

[Dbsubashi]

John, many other game systems measure that way, including pre-8th edition 40k. Your “friends” are probably confounding the rules from previous play experiences.